Optimizing Layout of Irregular Structures in Regular Layout Context

ABSTRACT

A plurality of regular wires are formed within a given chip level, each having a linear-shape with a length extending in a first direction and a width extending in a second direction perpendicular to the first direction. The plurality of regular wires are positioned according to a fixed pitch such that a distance as measured in the second direction between lengthwise centerlines of any two regular wires is an integer multiple of the fixed pitch. At least one irregular wire is formed within the given chip level and within a region bounded by the plurality of regular wires. Each irregular wire has a linear-shape with a length extending in the first direction and a width extending in the second direction. A distance as measured in the second direction between lengthwise centerlines of any irregular wire and any regular wire is not equal to an integer multiple of the fixed pitch.

CLAIM OF PRIORITY

This application is a continuation application under 35 U.S.C. 120 of prior U.S. application Ser. No. 13/898,155, filed May 20, 2013, issued as U.S. Pat. No. 9,754,878, on Sep. 5, 2017, which is a continuation application under 35 U.S.C. 120 of prior U.S. application Ser. No. 12/481,445, filed Jun. 9, 2009, issued as U.S. Pat. No. 8,448,102, on May 21, 2013, which:

1) claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 61/060,090, filed Jun. 9, 2008, and

2) is a continuation-in-part application under 35 U.S.C. 120 of U.S. application Ser. No. 12/013,342, filed Jan. 11, 2008, issued as U.S. Pat. No. 7,917,879, on Mar. 29, 2011, which claims priority under 35 U.S.C. 119(e) to both U.S. Provisional Patent Application No. 60/963,364, filed Aug. 2, 2007, and U.S. Provisional Patent Application No. 60/972,394, filed Sep. 14, 2007, and

3) is a continuation-in-part application under 35 U.S.C. 120 of prior U.S. application Ser. No. 12/212,562, filed Sep. 17, 2008, issued as U.S. Pat. No. 7,842,975, on Nov. 30, 2010, which is a continuation application under 35 U.S.C. 120 of U.S. application Ser. No. 11/683,402, filed Mar. 7, 2007, issued as U.S. Pat. No. 7,446,352, on Nov. 4, 2008, which claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 60/781,288, filed Mar. 9, 2006.

The disclosure of each above-identified patent application is incorporated herein by reference in its entirety.

BACKGROUND

A push for higher performance and smaller die size drives the semiconductor industry to reduce circuit chip area by approximately 50% every two years. The chip area reduction provides an economic benefit for migrating to newer technologies. The 50% chip area reduction is achieved by reducing the feature sizes between 25% and 30%. The reduction in feature size is enabled by improvements in manufacturing equipment and materials. For example, improvement in the lithographic process has enabled smaller feature sizes to be achieved, while improvement in chemical mechanical polishing (CMP) has in-part enabled a higher number of interconnect layers.

In the evolution of lithography, as the minimum feature size approached the wavelength of the light source used to expose the feature shapes, unintended interactions occurred between neighboring features. Today minimum feature sizes are being reduced below 45 nm (nanometers), while the wavelength of the light source used in the photolithography process remains at 193 nm. The difference between the minimum feature size and the wavelength of light used in the photolithography process is defined as the lithographic gap. As the lithographic gap grows, the resolution capability of the lithographic process decreases.

An interference pattern occurs as each shape on the mask interacts with the light. The interference patterns from neighboring shapes can create constructive or destructive interference. In the case of constructive interference, unwanted shapes may be inadvertently created. In the case of destructive interference, desired shapes may be inadvertently removed. In either case, a particular shape is printed in a different manner than intended, possibly causing a device failure. Correction methodologies, such as optical proximity correction (OPC), attempt to predict the impact from neighboring shapes and modify the mask such that the printed shape is fabricated as desired. However, the quality of the light interaction prediction is declining as process geometries shrink and as the light interactions become more complex.

In view of the foregoing, solutions are sought for improvements in circuit design and layout that can improve management of lithographic gap issues as technology continues to progress toward smaller semiconductor device features sizes.

SUMMARY

In one embodiment, a method is disclosed for placing irregular layout shapes in a dynamic array architecture. The method includes bracketing an irregular wire layout region within a portion of a chip level layout. The bracketing is done by placing a first regular wire layout shape on a first side of the irregular wire layout region, and by placing a second regular wire layout shape on a second side of the irregular wire layout region. The method also includes placing one or more irregular wire layout shapes within the irregular wire layout region. A first edge spacing is maintained between the first regular wire layout shape and an outer irregular wire layout shape within the irregular wire layout region nearest to the first regular wire layout shape. A second edge spacing is maintained between the second regular wire layout shape and an outer irregular wire layout shape within the irregular wire layout region nearest to the second regular wire layout shape. The first and second edge spacings are defined to optimize lithography of the first and second regular wire layout shapes and of the irregular wire layout shapes within the irregular wire layout region.

In one embodiment, a computer readable storage medium is disclosed to include a semiconductor chip layout recorded in a digital format. The semiconductor chip layout includes irregular layout shapes placed in a dynamic array architecture. Also in the semiconductor chip layout, an irregular wire layout region within a portion of a chip level layout is bracketed by a first regular wire layout shape on a first side of the irregular wire layout region and by a second regular wire layout shape on a second side of the irregular wire layout region. The semiconductor chip layout further includes one or more irregular wire layout shapes placed within the irregular wire layout region. A first edge spacing is maintained between the first regular wire layout shape and an outer irregular wire layout shape within the irregular wire layout region nearest to the first regular wire layout shape. A second edge spacing is maintained between the second regular wire layout shape and an outer irregular wire layout shape within the irregular wire layout region nearest to the second regular wire layout shape. The first and second edge spacings are defined to optimize lithography of the first and second regular wire layout shapes and of the irregular wire layout shapes within the irregular wire layout region.

In one embodiment, a method is disclosed for defining a virtual grate for a layout of a portion of a semiconductor chip level. The method includes an operation for identifying a preferred routing direction for a portion of a given chip level. The method also includes an operation for identifying each contact level related to the portion of the given chip level. Each identified contact level is defined by a respective related virtual grate defined by a respective set of parallel virtual lines extending in the preferred routing direction. Layout shapes within a given contact level are placed in accordance with the respective related virtual grate of the given contact level. The method further includes an operation for defining a trial virtual grate for the portion of the given chip level as a set of parallel virtual lines extending in the preferred routing direction. The set of parallel virtual lines of the trial virtual grate is defined to enable required connections between layout shapes placed in accordance with the trial virtual grate within the portion of the given chip level and layout shapes within each identified contact level. The method continues with an operation for determining whether a perpendicular spacing between adjacent virtual lines of the trial virtual grate provides for adequate lithographic reinforcement of layout shapes to be placed in accordance with the trial virtual grate. If the perpendicular spacing between adjacent virtual lines of the trial virtual grate is determined adequate, the method proceeds with recording the trial virtual grate as a final virtual grate of the portion of the given chip level. However, if the perpendicular spacing between adjacent virtual lines of the trial virtual grate is determined inadequate, the method proceeds by adjusting at least one related virtual grate of any identified contact level and by repeating the method operations beginning with the operation for defining a trial virtual grate for the portion of the given chip level.

Other aspects and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary CMOS transistor configuration, in accordance with one embodiment of the present invention;

FIG. 2A shows a flowchart of a method for defining a virtual grate for a given chip level, or portion thereof, in accordance with one embodiment of the present invention;

FIG. 2B shows virtual lines of a contact level virtual grate which indicate preferred placement locations in one dimension for contact level shapes, in accordance with one embodiment of the present invention;

FIG. 3A shows a flowchart of a method for placement of shapes such that the impact of using irregular wires in conjunction with the dynamic array architecture may be minimized, and re-alignment to a virtual grate occurs for regular shapes outside of a layout region where there are irregular wires, in accordance with one embodiment of the present invention;

FIG. 3B shows an exemplary layout defined in accordance with the method of FIG. 3A in which one irregular wire is placed such that a standard long edge-to-long edge spacing is used between one long edge of the irregular wire and a facing edge thereto of an adjacent and parallel regular wire, in accordance with one embodiment of the present invention;

FIG. 3C shows an exemplary layout defined in accordance with the method of FIG. 3A in which multiple irregular wires are placed such that a standard long edge-to-long edge spacing is used between one long edge of each of the irregular wires and a facing edge thereto of an adjacent and parallel regular wire, in accordance with one embodiment of the present invention;

FIG. 3D shows an exemplary layout defined in accordance with the method of FIG. 3A in which optimal spacing between facing long edges of adjacent regular and irregular wires and between facing long edges of adjacent irregular wires within an irregular wire layout region is based on minimization of differences between these long edge-to-long edge spacings within the irregular wire layout region, in accordance with one embodiment of the present invention;

FIG. 3E shows an exemplary layout that demonstrates how spacing variation can be reduced by increasing the number of irregular wires within an irregular wire layout region, in accordance with one embodiment of the present invention;

FIG. 3F shows a variant of the exemplary layout of FIG. 3B, defined in accordance with the method of FIG. 3A, in which one irregular wire is placed in conjunction with a sub-res wire within the irregular wire layout region, in accordance with one embodiment of the present invention;

FIG. 3G is an illustration showing a variant of the exemplary layout of FIG. 3C, defined in accordance with the method of FIG. 3A, in which two irregular wires are placed in conjunction with a sub-res wire within the irregular wire layout region, in accordance with one embodiment of the present invention;

FIG. 4 shows an exemplary layout for a diffusion level, defined in accordance with the method of FIG. 3A, in accordance with one embodiment of the present invention;

FIG. 5A shows an exemplary layout in which irregular wires have non-standard widths, which may or may not be equal to each other and which are smaller than a standard width for regular wires, in accordance with one embodiment of the present invention;

FIG. 5B shows an exemplary layout similar to that of FIG. 5A except that irregular wires, having widths that are less than standard width, are placed such that long edge-to-long edge spaces associated with irregular wires are defined to be similar to each other, but not necessarily equal to the standard spacing, in accordance with one embodiment of the present invention;

FIG. 5C shows an exemplary layout with irregular wires having widths that are less than a standard width, in accordance with one embodiment of the present invention;

FIG. 6 shows an exemplary layout implementing a method to reduce negative electrical or manufacturing influences between layout shapes or layout regions by interposing other layout shapes between them, in accordance with one embodiment of the present invention;

FIG. 7 shows a variation of the exemplary layout of FIG. 6 in which protective sub-res shapes are placed in lieu of protective regular wires, in accordance with one embodiment of the present invention;

FIG. 8A shows an exemplary layout within which end gaps are varied to improve manufacturability, in accordance with one embodiment of the present invention;

FIG. 8B shows an exemplary layout in which long regular wires are used to bound an irregular wire layout region, thereby serving as protective layout shapes between the irregular wire layout region and a surrounding layout area, in accordance with one embodiment of the present invention;

FIG. 8C shows a variation of the exemplary layout of FIG. 8B, in which sub-res shapes are used in lieu of long regular wires, in accordance with one embodiment of the present invention;

FIG. 8D shows a layout region immediately adjacent to a long edge of a linear layout shape, in accordance with one embodiment of the present invention;

FIG. 8E shows an exemplary layout in which regular wires of standard width are defined within a layout region, in accordance with one embodiment of the present invention;

FIG. 8F shows an exemplary layout that includes a symmetrical arrangement of irregular wires, in accordance with one embodiment of the present invention;

FIG. 8G shows a variation of the exemplary layout of FIG. 8F in which a layout shape is inserted between symmetrically arranged irregular wires, in accordance with one embodiment of the present invention;

FIG. 8H shows an exemplary layout in which irregular wires are arranged in an array defined by four layout shape columns and one layout shape row, in accordance with one embodiment of the present invention;

FIG. 9A shows an exemplary layout illustrating a method to reduce spacing variation by modifying one or more irregular wire widths such that long edge-to-long edge spacing after placement is satisfactory, in accordance with one embodiment of the present invention;

FIG. 9B shows an exemplary layout in which two irregular wires are successively placed between regular wires, in accordance with one embodiment of the present invention;

FIG. 9C shows an exemplary layout in which irregular shapes are placed between regular wires, in accordance with one embodiment of the present invention;

FIG. 10A shows an exemplary layout in which an irregular wire is placed such that its centerline is coincident with a virtual grate line, in accordance with one embodiment of the present invention;

FIG. 10B shows a variation of the exemplary layout of FIG. 10A in which the irregular wire is moved up to a virtual grate line, and a regular wire is moved up to another virtual grate line, in accordance with one embodiment of the present invention; and

FIG. 10C shows a variation of the exemplary layout of FIG. 10A in which layout shapes are inserted in long edge spaces on each side of the irregular wire, in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present invention.

Dynamic Array Architecture

The dynamic array architecture represents a semiconductor device design paradigm in which linear-shaped layout features are defined along a regular-spaced virtual grate (or regular-spaced virtual grid) in a number of levels of a cell, i.e., in a number of levels of a semiconductor chip. The virtual grate is defined by a set of equally spaced, parallel virtual lines extending across a given level in a given chip area. The virtual grid is defined by a first set of equally spaced, parallel virtual lines extending across a given level in a given chip area in a first direction, and by a second set of equally spaced, parallel virtual lines extending across the given level in the given chip area in a second direction, where the second direction is perpendicular to the first direction. In one embodiment, the virtual grate of a given level is oriented to be substantially perpendicular to the virtual grate of an adjacent level. However, in other embodiments, the virtual grate of a given level is oriented to be either perpendicular or parallel to the virtual grate of an adjacent level.

In one embodiment, each linear-shaped layout feature of a given level is substantially centered upon one of the virtual lines of the virtual grate associated with the given level. A linear-shaped layout feature is considered to be substantially centered upon a particular line of a virtual grate when a deviation in alignment between of the centerline of the linear-shaped layout feature and the particular line of the virtual grate is sufficiently small so as to not reduce a manufacturing process window from what would be achievable with a true alignment between of the centerline of the linear-shaped layout feature and the line of the virtual grate.

In one embodiment, the above-mentioned manufacturing process window is defined by a lithographic domain of focus and exposure that yields an acceptable fidelity of the layout feature. In one embodiment, the fidelity of a layout feature is defined by a characteristic dimension of the layout feature. Also, it should be understood that the centerline of a given linear-shaped layout feature is defined as a virtual line that passes through the cross-sectional centroid of the linear-shaped layout feature at all points along its length, wherein the cross-sectional centroid of the linear-shaped layout feature at any given point along its length is the centroid of its vertical cross-section area at the given point.

In another embodiment, some linear-shaped layout features in a given level may not be centered upon a virtual line of the virtual grate associated with the given level. However, in this embodiment, the linear-shaped layout features remain parallel to the virtual lines of the virtual grate, and hence parallel to the other linear-shaped layout features in the given level. Therefore, it should be understood that the various linear-shaped layout features defined in a layout of a given level are oriented to extend across the given level in a parallel manner.

Also, in the dynamic array architecture, in one embodiment, each linear-shaped layout feature is defined to be devoid of a substantial change in direction along its length. The lack of substantial change in direction of a linear-shaped layout feature is considered relative to the line of the virtual grate along which the linear-shaped layout feature is defined. In one embodiment, a substantial change in direction of a linear-shaped layout feature exists when the width of the linear-shaped layout feature at any point thereon changes by more than 50% of the nominal width of the linear-shaped layout feature along its entire length. In another embodiment, a substantial change in direction of a linear-shaped layout feature exists when the width of the linear-shaped layout feature changes from any first location on the linear-shaped layout feature to any second location on the linear-shaped layout feature by more that 50% of the linear-shaped layout feature width at the first location. Therefore, it should be appreciated that the dynamic array architecture specifically avoids the use of non-linear-shaped layout features, wherein a non-linear-shaped layout feature includes one or more bends within a plane of the associated level.

In the dynamic array architecture, variations in a vertical cross-section shape of an as-fabricated linear-shaped layout feature can be tolerated to an extent, so long as the variation in the vertical cross-section shape is predictable from a manufacturing perspective and does not adversely impact the manufacture of the given linear-shaped layout feature or its neighboring layout features. In this regard, the vertical cross-section shape corresponds to a cut of the as-fabricated linear-shaped layout feature in a plane perpendicular to the centerline of the linear-shaped layout feature. It should be appreciated that variation in the vertical cross-section of an as-fabricated linear-shaped layout feature along its length can correspond to a variation in width along its length. Therefore, the dynamic array architecture also accommodates variation in the width of an as-fabricated linear-shaped layout feature along its length, so long as the width variation is predictable from a manufacturing perspective and does not adversely impact the manufacture of the linear-shaped layout feature or its neighboring layout features.

Additionally, different linear-shaped layout features within a given level can be designed to have the same width or different widths. Also, the widths of a number of linear-shaped layout features defined along adjacent lines of a given virtual grate can be designed such that the number of linear-shaped layout features contact each other so as to form a single linear-shaped layout feature having a width equal to the sum of the widths of the number of linear-shaped layout features.

Within a given level defined according to the dynamic array architecture, proximate ends of adjacent, co-aligned linear-shaped layout features may be separated from each other by a substantially uniform gap. More specifically, adjacent ends of linear-shaped layout features defined along a common line of a virtual grate are separated by an end gap, and such end gaps within the level associated with the virtual grate may be defined to span a substantially uniform distance. Additionally, in one embodiment, a size of the end gaps is minimized within a manufacturing process capability so as to optimize filling of a given level with linear-shaped layout features.

Also, in the dynamic array architecture, a level can be defined to have any number of virtual grate lines occupied by any number of linear-shaped layout features. In one example, a given level can be defined such that all lines of its virtual grate are occupied by at least one linear-shaped layout feature. In another example, a given level can be defined such that some lines of its virtual grate are occupied by at least one linear-shaped layout feature, and other lines of its virtual grate are vacant, i.e., not occupied by any linear-shaped layout features. Furthermore, in a given level, any number of successively adjacent virtual grate lines can be left vacant. Also, the occupancy versus vacancy of virtual grate lines by linear-shaped layout features in a given level may be defined according to a pattern or repeating pattern across the given level.

Additionally, within the dynamic array architecture, vias and contacts are defined to interconnect a number of the linear-shaped layout features in various levels so as to form a number of functional electronic devices, e.g., transistors, and electronic circuits. Layout features for the vias and contacts can be aligned to a virtual grid, wherein a specification of this virtual grid is a function of the specifications of the virtual grates associated with the various levels to which the vias and contacts will connect. Thus, a number of the linear-shaped layout features in various levels form functional components of an electronic circuit. Additionally, some of the linear-shaped layout features within various levels may be non-functional with respect to an electronic circuit, but are manufactured nonetheless so as to reinforce manufacturing of neighboring linear-shaped layout features. It should be understood that the dynamic array architecture is defined to enable accurate prediction of semiconductor device manufacturability with a high probability.

In view of the foregoing, it should be understood that the dynamic array architecture is defined by placement of linear-shaped layout features on a regular-spaced grate (or regular-spaced grid) in a number of levels of a cell, such that linear-shaped layout features in a given level of the cell are oriented to be substantially parallel with each other in their traversal direction across the cell. Also, in one embodiment of the dynamic array architecture, prior to process compensation technique (PCT) processing, each linear-shaped layout feature is defined to be devoid of a substantial change in direction relative to its traversal direction.

Nomenclature

In the figures and text herein, certain naming conventions are applied as follows:

-   -   VG: virtual grate;     -   VG lines: virtual lines of a virtual grate;     -   Wire: a linear shaped layout feature on a given level with a         centerline parallel to a VG line of the given level and region         thereof under consideration;     -   Conductive layout feature: a layout shape on a level such as         active, gate electrode, local interconnect, metal (interconnect)         level, or other level that may be conductive and is not a         contact or via level;     -   Long edge: a linear shaped layout feature's edge that is         oriented parallel to VG lines of the level in which the linear         shaped layout feature is defined, regardless of the aspect ratio         of the linear shaped layout feature;     -   Line end: a linear shaped layout feature edge that is oriented         orthogonal (perpendicular) to VG lines for the level in which         the linear shaped layout feature is defined;     -   End gap: a space between line ends of linear shaped layout         features placed line end-to-line end;     -   Parallel wires: wires having parallel long edges and offset         centerlines;     -   Width: a wire dimension orthogonal to the VG line upon which the         wire is placed;     -   Regular wires: a number of wires of common width placed         according to a VG of a given level;     -   Standard gap (standard spacing): a distance measured         perpendicularly between facing long edges of adjacent and         parallel regular wires;     -   Irregular wire: a wire in a given level that does not have the         common width of other regular wires in the given level or that         is not centered on a VG line of the given level;     -   Irregular spacing: a distance measured perpendicularly between         long edges of wires that is not equal to the standard gap         (standard spacing);     -   Spacing variation: a difference between irregular spacing and         standard gap (standard spacing). In one embodiment, spacing         variation may be defined as a maximum spacing variation within         an area of a given level. In another embodiment, spacing         variation may be defined as an average value within an area of a         given level. In another embodiment, spacing variation may be         defined based on a single instance of irregular spacing;     -   Sub-resolution (sub-res) shape: a shape that is drawn but         intentionally not manufactured due to having one or more         dimensions below the resolution capability of a manufacturing         system. For example, at least one dimension (length or width,         etc.) of the sub-res shape may be small enough to guarantee that         the sub-res shape will not be resolved as a manufactured         feature, even when the sub-res shape is placed in compliance         with normal edge spacing constraints relative to other layout         shapes;     -   Gate: a gate electrode feature defined as part of a transistor;     -   Irregular wire layout region: a layout region bounded by regular         wires within which one or more irregular wires are placed.

Exemplary Embodiments

In one embodiment, a layout defined in accordance with the dynamic array architecture may include the following attributes: 1) shapes are rectangular, i.e., linear-shaped, 2) wire and contact pitch is substantially constant in a direction orthogonal to routing, 3) wire width is substantially constant, 4) side-to-side and end-of-line wire spacings are substantially constant, 5) overall shape density is as uniform as possible, and 6) the proximity of gaps in wires to other wire shapes is managed to avoid lithographic disturbance. It should be understood, however, that in some embodiments, a layout defined in accordance with the dynamic array architecture may not include all of the attributes associated with the above-mentioned embodiment. Methods and techniques are disclosed herein for enhancing layout in situations where particular layout areas or layout shapes do not strictly follow the dynamic array architecture but are contained within a layout that substantially follows the dynamic array architecture.

An exemplary CMOS transistor configuration is shown in FIG. 1. Gate electrode (gate) wires 160-162 each have a different width W2 in comparison to a standard width W1 of gate wires 110-118. Gate wires 110-117 and 160-162 form gate electrodes of transistors where they overlap with active shapes 120-122. Gate level wire 118 is an example of a wire on a gate electrode level that does not traverse an active level and is not used to form a gate electrode. Source or drain contact shapes such as 140-142 and gate contacts such as 143 and 144 are indicated as examples of shapes on the contact (CON) level.

Each gate electrode is defined to extend beyond the edges of its underlying active region. Each portion of a gate electrode that extends beyond an edge of its underlying active region is referred to as an overlap portion of the gate electrode. A traversal direction of a gate electrode relative to its underlying active region is defined as a direction that extends between the overlap portions of the gate electrode and that is perpendicular to the edges of the underlying active region beyond which the overlap portions of the gate electrode extend. For example, considering gate electrode feature 114, overlapping portions 114A and 114B extend beyond active region edges 121A and 121B, respectively. Therefore, arrow 170 represents the traversal direction of gate electrode 114, as arrow 170 extends between the overlap portions 114A and 114B of the gate electrode 114 and is perpendicular to the edges 121A and 121B of the underlying active region 121 beyond which the overlap portions 114A and 114B of the gate electrode 114 extend.

Gate dimensions which run perpendicular to the traversal direction of the gate over its underlying active region, such as W1 and W2, are referred to as gate channel lengths. Use of multiple gate channel lengths in a given level represents one of many cases in which multiple values for a given type of dimension, e.g., width, can be applied to different layout shapes on a given level. This invention applies to any level in which non-standard shape dimensions may occur, wherein a given shape dimension is considered non-standard in a given level when a value of the given shape dimension varies among layout features in the given level. For ease of discussion, the principles of the present invention are described herein with respect to a gate level in various exemplary embodiments. However, it should be understood that the principles of the present invention as referenced to a gate level in the exemplary embodiments herein can be equally applied to any chip level. For example, the principles of the present invention can be equally applied to an active level, a local interconnect level, a metal (interconnect) level, a contact level, a via level, or essentially any other chip level.

Also shown in FIG. 1 are lines 100-103 of a virtual grate (VG) for the gate level. The virtual lines 100-103 are spaced apart from each other by a constant line-to-line pitch P1. FIG. 2A is an illustration showing a flowchart of one method for defining a VG for a given chip level, or portion thereof, referred to as the given level hereafter. The method includes an operation 201 for identifying a preferred routing direction for the given level. The method also includes an operation 203 for identifying each related contact level, wherein a related contact level includes at least one shape that is to make contact with a shape in the given level. Virtual lines of a contact level VG indicate preferred placement locations in one dimension for contact level shapes, even if contact level shapes are not present on every virtual line of the contact level VG in a layout under consideration. An example of this may be seen in FIG. 2B, where a VG for gate CON shapes includes virtual lines 181, 183, 185, and 187. The example of FIG. 2B shows gate CON shapes 142 and 143 present on VG lines 183 and 187, and no gate CON shapes present on the other VG lines 181 and 185 for the gate CON level.

The method described in FIG. 2A also includes an operation 207 for defining the VG for the given level as a set of evenly spaced virtual lines that represent centerline locations of wires to be placed on the given level. The VG for the given level is defined such that a number of its virtual lines coincide with virtual lines of the contact level VG, such that wires placed in the given level according to the VG of the given level can provide sufficient coverage of contacts placed according to the contact level VG lines, wherein the contact level VG lines are commonly oriented with the VG lines of the given level and hence with the routing direction of wire placed in the given level. In FIG. 2B, a VG for source/drain CON shapes 140, 141, and 144 includes virtual lines 180, 182, 184, 186, and 188. It should be appreciated that source/drain CON shapes 140, 141, and 144 are electrically connected to active region 120. A VG for MET1 level shapes 170-178 includes VG lines 180-188. Because the MET1 level shapes are related (i.e., connect) to the source/drain CON shapes (140, 141, 144) and/or to the gate CON shapes (142, 143), the VG for the MET1 level includes both the virtual lines (181, 183, 185, 187) of the gate CON VG, and the virtual lines (180, 182, 184, 186, 188) of the source/drain CON VG. A VG for gate level shapes 200-203 includes VG lines 181, 183. 185, and 187. Because the gate level shapes (200-203) are related (i.e., connect) to the gate CON shapes (142, 143), the VG for the gate level includes the virtual lines (181, 183, 185, 187) of the gate CON VG. As shown in FIG. 2B, the VG for the gate level is defined by parallel virtual lines (181, 183, 185, 187) spaced at a line-to-line pitch P1.

The method of FIG. 2A further includes an operation 209 for determining whether or not the line-to-line spacing of the VG for the given level allows for enforcement of the dynamic array architecture within the given level so as to ensure optimal manufacturability of shapes in the given level. Examples of sub-optimal VG pitches include, but are not limited to: 1) a VG pitch that may be too large for shapes placed in accordance therewith to provide sufficient lithographic reinforcing benefits to each other, or 2) a VG pitch that may be too small to identify shape placements in accordance therewith, such that shapes are sufficiently regularly spaced and/or such that shapes are positioned for optimal lithography or manufacturing. If the VG pitch for the given level is acceptable, the method proceeds with an operation 214 in which the VG is recorded on a data storage device 216. However, if the VG pitch for the given level is NOT acceptable, the method proceeds with an operation 213. In operation 213, an adjustment is made to the VG of one or more of the related contact levels as previously identified in operation 203. Following operation 213, the method reverts back to operation 207.

With reference back to the exemplary embodiment of FIG. 1, each space SS between the long edges of neighboring gate wires 110-118 and 160-162 is substantially equivalent. Such consistency in long edge-to-long edge spacing may be beneficial to manufacturing results. However, since the widths W1 and W2 of the gate wires are not equal, use of the substantially equivalent long edge-to-long edge spacing SS causes some gate wire centerlines to be placed off of the virtual lines 100-103 of the gate level VG. For example, centerlines of shape 160 (having the non-standard width W2) and shapes 115 and 116 therebelow are not aligned with the VG lines 101-103, respectively. Similarly, in this example, centerlines of shape 161 (having the non-standard width W2) and shapes 102 and 103 therebelow are not aligned with the VG lines 101-103, respectively. Therefore, in this embodiment, gate wire shapes below VG line 100 are not placed so as to have their respective centerlines align with a VG, and consequently do not comply with the dynamic array architecture attribute regarding placement of linear features according to a VG within a given layout area, wherein the VG is defined by a set of parallel virtual lines spaced according to a substantially constant line-to-line pitch. Additionally, because the gate wire shapes below VG line 100 do not comply with the dynamic array architecture attribute regarding placement of linear features according to a VG within a given layout area, definition of the gate wire shapes below VG line 100 may not be optimal for manufacturing or layout efficiency.

FIG. 3A is an illustration showing a flowchart of a method for placement of shapes such that the impact of using irregular wires in conjunction with the dynamic array architecture may be minimized, and re-alignment to a VG occurs for regular shapes outside of a layout region where there are irregular wires. The method includes an operation 3A01 in which a first irregular wire is placed next to a first regular wire. It should be understood that numerical designations used for particular wires, e.g., “first” irregular wire, “first” regular wire, etc., do not denote absolute wire position within a layout, but rather are used to differentiate between wires. Determination of the distance between facing long edges of the first irregular wire and the first regular wire may be based on one or more of the following considerations: 1) making such a distance substantially equivalent to a standard distance between adjacent facing long edges of regular wires, 2) providing sufficient room for a dummy shape or a sub-res shape to be inserted between the first irregular wire and the first regular wire, 3) using a distance that enables even spacing between centerlines of irregular wires within the irregular wire layout region, 4) using a distance that enables even spacing between facing long edges of adjacently placed irregular wires within the irregular wire layout region, 5) forcing irregular wires to be centered on a VG line, or 6) enabling some other desired spacing pattern for layout shapes within the irregular wire layout region, among others. The first irregular wire may belong to a group of N irregular wires that are parallel and adjacent, or it may be a solitary irregular wire with regular wires placed parallel and adjacent to both long edges of the solitary irregular wire. It should be understood that in the case of a solitary wire placed within the irregular wire layout region (N=1), the first and last irregular wire mentioned in the method of FIG. 3A refer to the same irregular wire.

The method also includes an operation 3A02 in which a calculation is made of a number of VG routing lines within the distance required to fit all remaining irregular wires parallel to the first irregular wire. In one embodiment, the calculation of operation 3A02 takes into account the space required to allow a regular wire to be placed on a VG line beyond the area with irregular wires. The method also includes an operation 3A03 in which a second regular wire is placed with it's centerline co-linear with a first available VG line beyond the VG line required to place the N-th irregular shape, as calculated in operation 3A02. In the decision operation 3A05, if the number of parallel irregular wires is greater than one (N>1), the method continues with an operation 3A07.

In the operation 3A07, a last irregular wire is placed adjacent (albeit spaced apart from) and parallel to the second regular wire. Determination of the distance between facing long edges of last irregular wire and second regular wire may be based on placement considerations for the irregular wire such as those considerations described for operation 3A01. The method continues with an operation 3A09 in which all other irregular wires between the first and last irregular wires are placed. Operation 3A09 may involve placement considerations similar to those described for operation 3A01.

From the operation 3A09, the method proceeds with an operation 3A11. Also, with reference back to the decision operation 3A05, if the number of parallel irregular wires is one (N=1), the method proceeds to operation 3A11. In the operation 3A11, an evaluation is made regarding the use of sub-res shapes, which may provide lithographic reinforcement to shapes in their vicinity, thereby resulting in improved manufacturing results. If the evaluation of operation 3A11 determines that sub-res shapes are not to be used, the method proceeds with an operation 3A14 for recording the layout on the data storage device 216. If the evaluation of operation 3A11 determines that sub-res shapes are to be used, the method proceeds to an operation 3A13, in which sub-res shapes are formed and placed. Sub-res shape formation is the determination of the polygonal outline of a sub-res shape. Sub-res shape placement may be in spaces adjacent to long edges of irregular or regular wires and may be influenced by considerations for optimal spacing, as described in conjunction with operation 3A01. Following the completion of operation 3A13, the method proceeds with the operation 3A14 for recording the layout on the data storage device 216.

It should be understood that for parallel and adjacent placement of more than one successive irregular wire, the method described in FIG. 3A has an operational order that provides for regular wire bracketing of the region of irregular wires, prior to placement of multiple irregular wires. This operational order facilitates calculation of where to place the last irregular wire (operation 3A07), and other irregular wires between the first and last irregular wires. In addition to the foregoing, however, it should be understood that the various operations of the method of FIG. 3A may be performed in a non-sequential order in some embodiments. Additionally, it should be understood that the method of FIG. 3A represents one exemplary method for achieving the layout features and principles illustrated in the figures herein. It should be appreciated that other methods, including variants of the method of FIG. 3A, may be utilized to achieve the layout features and principles illustrated in the figures herein. Moreover, it should be understood that the methods described herein and the layouts defined in accordance with those methods are not restricted to a particular VG or to a particular wire routing direction. Specifically, the methods described herein can be applied to a layout region of any chip level and can be implemented using either a vertically oriented VG or a horizontally oriented VG.

In one embodiment, an optimal spacing between facing long edges of a regular wire and an irregular wire, or between facing long edges of two adjacent irregular wires, is determined by maximizing the number of times that these long edge-to-long edge spacings are equal to a standard spacing. In this embodiment, the standard spacing is defined as a distance measured perpendicularly between facing long edges of adjacent and parallel regular wires.

FIG. 3B is an illustration showing an exemplary layout defined in accordance with the method of FIG. 3A in which one irregular wire 360 is placed (N=1) such that a standard long edge-to-long edge spacing SS is used between one long edge of the irregular wire and a facing edge thereto of an adjacent and parallel regular wire 320. In the exemplary layout of FIG. 3B, each of regular wires 310-314, 320, 323, and 324 having width W1 is placed in a centered manner on a respective virtual line 300-304 of a VG. Adjacent virtual lines 300-304 of the VG are spaced at a substantially constant pitch P1. The single irregular wire 360 has a width W2 and is placed such that the spacing from a first of its long edges to the facing long edge of the parallel and adjacent regular wire 320 is set to the standard spacing SS. As a result, the distance between a second long edge of the irregular wire 360 (opposite to the first long edge) and a facing long edge thereto of the adjacent and parallel regular wire 323 may be non-standard, as illustrated by non-standard spacing S3B1 in FIG. 3B. A spacing variation (SV3B) in this example is defined as a difference between the non-standard spacing S3B1 and the standard spacing SS, i.e., SV3B=S3B1−SS.

In FIG. 3B, regular wire 323 and regular wires below it, such as regular wire 324, are centered on a VG virtual line. In other words, regular wires can be re-aligned to the VG beyond the irregular wire layout region within which the irregular wires are placed. Also, re-alignment of regular wires to the VG may commence at a first virtual line instance of the VG that is a sufficient distance away from an outer irregular wire, wherein the outer irregular wire is peripherally placed within the irregular wire layout region. If the irregular wire layout region contains one irregular wire, then the one irregular wire is considered a peripherally placed irregular wire, and hence an outer irregular wire. If the irregular wire layout region contains two irregular wires, then each of the two irregular wires is considered a peripherally placed irregular wire, and hence an outer irregular wire. Additionally, if the irregular wire layout region includes three or more irregular wires, numbered in an adjacent sequential manner as irregular wire one through irregular wire N, then each of irregular wire one and irregular wire N is considered a peripherally placed irregular wire, and hence an outer irregular wire. Moreover, a sufficiency of the distance away from the outer irregular wire at which re-alignment of regular wires to the VG may commence can be evaluated based on whether both the outer irregular wire and the regular wire adjacent thereto are within an applicable manufacturing process window as defined by a lithographic domain of focus and exposure that yields an acceptable fidelity of both the outer irregular wire and the regular wire adjacent thereto. Based on the example of FIG. 3B, and other examples described hereafter, is should be appreciated that the method of FIG. 3A provides a beneficial effect of limiting a size of the irregular wire layout region within a given level.

As shown in FIG. 3B, line ends of shapes on different VG lines may or may not be aligned. For example, line ends of wires 311 and 312 are not aligned, but line ends of wires 313 and 314 are aligned. Furthermore, a distance between facing line ends of wires which overlie a common virtual line of the VG, i.e., end gap, may or may not be constant. For example, an end gap LE3B1 between facing line ends of wires 310 and 320 is different than an end gap LE3B2 between facing line ends of wires 311 and 360. It should be understood that unless otherwise specified, end gaps and alignments between line ends of adjacent parallel wires, as illustrated in the embodiments herein, are provided by way of example and do not imply a restriction on end gaps or line end alignments. Also, it should be understood that unless otherwise specified, irregular wire widths as illustrated in the exemplary embodiments herein do not imply a restriction or requirement with regard to irregular wire widths or relationships therebetween.

FIG. 3C is an illustration showing an exemplary layout defined in accordance with the method of FIG. 3A in which multiple irregular wires 360 and 362 (N>1) are placed such that a standard long edge-to-long edge spacing SS is used between one long edge of each of the irregular wires 360 and 362 and a facing edge thereto of an adjacent and parallel regular wire 320 and 324, respectively. Thus, the exemplary layout of FIG. 3C has a standard gap SS between long edges of first and last irregular wires 360 and 362 and facing long edges of regular wires 320 and 324, respectively. In FIG. 3C, the two irregular wires 360 and 362 (N=2) have irregular widths W2 and W3, respectively. Use of the standard gap SS outboard of both the first and last irregular wires 360 and 362 with N=2 results in only one irregular spacing S3F1 and a spacing variation SV3F=S3F1−SS.

In one embodiment, optimal spacing between facing long edges of adjacent regular and irregular wires and/or between facing long edges of adjacent irregular wires within an irregular wire layout region is based on minimization of differences between these long edge-to-long edge spacings within the irregular wire layout region. FIG. 3D is an illustration showing an exemplary layout defined in accordance with the method of FIG. 3A in which optimal spacing between facing long edges of adjacent regular and irregular wires and between facing long edges of adjacent irregular wires within an irregular wire layout region is based on minimization of differences between these long edge-to-long edge spacings within the irregular wire layout region. In the exemplary layout of FIG. 3D, the long edges of wires 360 and 362 are separated from facing long edges of regular wires 320 and 324, respectively, by spacings S3G1 and S3G3, which is not equal to the standard spacing SS. This forces a reduction in a space S3G2 between irregular wires 360 and 362, as compared to the corresponding spacing S3F1 between irregular wires 360 and 362 in FIG. 3C. It is possible to make each of long edge-to-long edge spacings S3G1, S3G2, and S3G3 more similar to the standard spacing SS than long edge-to-long edge spacing S3F1 from FIG. 3C.

FIG. 3D illustrates how a maximum spacing variation SV3G for the irregular wire layout region may be reduced by minimizing differences between the long edge-to-long edge spacings within the irregular wire layout region, wherein SV3G=MAX(S3G1,S3G2,S3G3)−SS. Generally speaking, maximum spacing variation within an irregular wire layout region is minimized when long edge-to-long edge spacings within the irregular wire layout region are equalized. For example, in the embodiment of FIG. 3D, the maximum spacing variation SV3G within the irregular wire layout region is minimized when long edge-to-long edge spacings within the irregular wire layout region are equal, i.e., when S3G1=S3G2=S3G3. It should be appreciated that reduction of maximum or average spacing variation in an irregular wire layout region may be beneficial to manufacturing.

In another embodiment, optimal definition and placement of irregular wires within an irregular wire layout region may require that a spacing between facing long edges of adjacent regular and irregular wires and/or between facing long edges of adjacent irregular wires within the irregular wire layout region be based on criteria other than minimization of differences between the long edge-to-long edge spacings within the irregular wire layout region. Consequently, optimal definition and placement of irregular wires within an irregular wire layout region may require that a number of long edge-to-long edge spacings within the irregular wire layout region be intentionally defined different from a standard long edge-to-long edge spacing. For example, due to non-standard widths of irregular wires or other considerations, the optimum spacing between a long edge of an irregular wire and a facing long edge of an adjacent wire (regular or irregular) may not be the same as the standard spacing between facing long edges of two adjacent regular wires. For example, in the embodiment of FIG. 3D, the optimum long edge-to-long edge spacings S3G1, S3G2, S3G3 within the irregular wire layout region may be set according to irregular wire spacing optimization criteria other than minimization of the maximum spacing variation SV3G within the irregular wire layout region.

In one embodiment, spacing variation may be reduced by increasing the number N of parallel and adjacently placed irregular wires within the irregular wire layout region. Increasing the number N of irregular wires may reduce spacing variation for certain values of irregular wire width and long edge-to-long edge wire spacing within the irregular wire layout region, including spacings between facing long edges of adjacent regular and irregular wires and between facing long edges of adjacent irregular wires within the irregular wire layout region. A long edge-to-long edge spacing adjustment to be applied across an irregular wire layout region, to enable centering of two regular wires on respective virtual lines of the VG bordering the irregular wire layout region, can be shared among more long edge-to-long edge wire spaces within the irregular wire layout region when the number N of irregular wires is increased. Therefore, increasing the number N of irregular wires within the irregular wire layout region may reduce a magnitude of individual wire spacing adjustment within the irregular wire layout region that is necessary to minimize spacing variation.

FIG. 3E is an illustration showing an exemplary layout that demonstrates how spacing variation can be reduced by increasing the number N of irregular wires within an irregular wire layout region. Irregular wires 360-362 are placed in a first irregular wire layout region within which an equal long edge-to-long edge wire spacing S3J1 is utilized. Irregular wires 370-371 are placed in a second irregular wire layout region within with an equal long edge-to-long edge wire spacing S3J2 is utilized. In the exemplary layout of FIG. 3E, each of irregular wires 360-362 and 370-371 has a width W2. Equal irregular wire spacings (S3J1 and S3J2, respectively) and equal irregular wire width (W2) are utilized in the exemplary layout of FIG. 3E for ease of description. However, it should be understood that use of an equal irregular wire spacing and use of an equal irregular wire width is not a pre-requisite for implementing the embodiment in which spacing variation is reduced by increasing the number N of irregular wires within an irregular wire layout region.

A term NVG is defined as a number of virtual lines of the VG that are located between the two regular wires which bound the irregular wire layout region. For the first irregular wire region including irregular wires 360-362, NVG equals 4 and includes virtual lines 301-304. For the second irregular wire region including irregular wires 370-371, NVG equals 3 and includes virtual lines 301-303. In the example of FIG. 3E, a standard spacing SS between regular wires is defined as SS=P1−W1, wherein P1 is the VG pitch and W1 is a width of the regular wires (310-315, 320, 325, 330, 334). For each irregular wire layout region, irregular spacing S3Jn=((NVGn+1)*P1−W1−Nn*W2)/(Nn+1), wherein (n) identifies the irregular wire layout region. For the first irregular wire layout region (n=1) including irregular wires 360-362, N1=3 and NVG1=4, thereby yielding irregular spacing S3J1=(5P1−W1−3*W2)/4. For the second irregular wire layout region (n=2) including wires 370-371, N2=2 and NVG2=3, thereby yielding irregular spacing S3J2=(3P1−W1−2*W2)/3. For discussion purposes consider that W2=2*W1 and P1=3*W1. Then, SS=2*W1, S3J1=2*W1, and S3J2, (4/3)*W1. For the first irregular wire layout region, spacing variation SVR1=SS−S3J1=0. For the second irregular wire layout region, spacing variation SVR2=SS−S3J2, (2/3)*W1. Therefore, the exemplary layout of FIG. 3E demonstrates how an increase in the number N of irregular wires within an irregular wire layout region serves to reduce spacing variation.

FIG. 3F is an illustration showing a variant of the exemplary layout of FIG. 3B, defined in accordance with the method of FIG. 3A, in which one irregular wire 360 is placed (N=1) in conjunction with a sub-res wire 390 within the irregular wire layout region. The sub-res wire 390 is defined to have a width SRW, and is placed between irregular wire 360 and regular wire 323. Use of the sub-res wire 390 eliminates the large wire spacing S3B1, as shown in FIG. 3B, and introduces smaller wire spacings S3D1 and S3D2. It should be noted that as compared to wire spacing S3B1, both of wire spacings S3D1 and S3D2 are closer to the standard spacing SS. Therefore, use of the sub-res wire 390 improves on the embodiment described in FIG. 3B in that spacing variation is reduced, which may be beneficial to manufacturing.

FIG. 3G is an illustration showing a variant of the exemplary layout of FIG. 3C, defined in accordance with the method of FIG. 3A, in which two irregular wires 360 and 362 are placed (N=2) in conjunction with a sub-res wire 391 within the irregular wire layout region. The sub-res wire 391 is defined to have a width SRW, and is placed between irregular wire 360 and irregular wire 362. Use of the sub-res wire 391 eliminates the large wire spacing S3F1, as shown in FIG. 3C, and introduces smaller wire spacings S3E2 and S3E3. It should be noted that as compared to wire spacing S3F1, both of wire spacings S3E2 and S3E3 are closer to the standard spacing SS. Therefore, use of the sub-res wire 391 improves on the embodiment described in FIG. 3C in that spacing variation is reduced, which may be beneficial to manufacturing.

It should be understood that the methods and layout techniques disclosed herein can be applied to any chip level. FIG. 4 shows an exemplary layout for a diffusion level, defined in accordance with the method of FIG. 3A. In one embodiment, layout shapes shown in FIG. 4 correspond to doped silicon regions, and may be referred to as active shapes or diffusion shapes. A VG for the diffusion level is defined by virtual lines 400-404. A number of regular diffusion shapes 410-414, 420, 424, 430, and 434 are defined to have standard width W41, and are placed with a standard spacing S40. Irregular diffusion shape 460 of width W42 is placed such that the standard spacing S40 exists between its outboard long edge and a facing long edge of adjacent regular diffusion shape 420. In one embodiment, a vacant irregular spacing S44 exists between facing long edge of irregular diffusion shape 460 and regular diffusion shape 424. In another embodiment, a sub-res shape 430 is inserted between irregular diffusion shape 460 and regular diffusion shape 424, resulting in irregular spacings S41 and S42. As compared to irregular spacing S44, irregular spacings S41 and S42 may be more similar to standard spacing SS, thereby providing a reduced spacing variation as compared to the embodiment without the sub-res shape 430. In another embodiment, multiple irregular diffusion shapes 461 and 462 are placed between parallel regular diffusion shapes 430 and 434. In this embodiment, spacings extending perpendicularly away from long edges of irregular diffusion shapes 461 and 462 are shown as S43, S44, and S45. In one embodiment, spacings S43-S45 are made similar or equal to each other to reduce the maximum spacing variation between standard spacing S40 and spacings S43-S45.

In some embodiments an irregular wire width may be smaller than a standard wire width. FIG. 5A shows an exemplary layout in which irregular wires 660-664 have non-standard widths W60-W64, which may or may not be equal to each other and which are smaller than a standard width W6 for regular wires 610-615, 620, and 625. A standard spacing SS6 is defined between facing long edges of adjacent regular wires 610-615. In FIG. 5A, irregular wires 660-664 are placed to maximize the occurrence of standard spacing SS6 within the irregular wire layout region. Generally speaking, the number N of irregular wires in an irregular wire layout region, and the respective widths thereof, may be defined such that for a given VG pitch it is not possible to place each irregular wire to have long edge-to-long edge spacings equivalent to the standard spacing. For example, the number N=5 of irregular wires 660-664 in the irregular wire layout region of FIG. 5A, and the respective widths thereof W60-W64, may be defined such that for a given VG (virtual lines 600-605) of pitch P6 it is not possible to place each irregular wire 660-664 to have long edge-to-long edge spacings equivalent to the standard spacing SS6. Spacing of irregular wires 660-664 to maximize the occurrence of standard spacing SS6 results in a single non-standard spacing S6A1 between facing long edges of adjacently placed irregular wires 662 and 663. A spacing variation SV6A1 for the dimension S6A1 is expressed as: SV6A1=S6A1−SS6.

FIG. 5B shows an exemplary layout similar to that of FIG. 5A except that irregular wires 660-664, having widths W60-W64 that are less than standard width W6, are placed such that long edge-to-long edge spaces S6B1-S6B6 associated with irregular wires 660-664 are defined to be similar to each other, but not necessarily equal to the standard spacing SS6. Maximum spacing variation (SV6B=|MAX(S6B1,S6B2,S6B3,S6B4,S6B5,S6B6)−SS6|) may be minimized for this exemplary layout when irregular spacings S6B1 through S6B6 are equalized. With equal irregular spacings S6B1 through S6B6, the maximum spacing variation SV6B can be expressed as: SV6B=|S6B1−SS6|. This spacing variation SV6B may be less than the maximum spacing variation SV6A for the layout of FIG. 5A, because the extra space required to re-synchronize regular wires to the VG at the boundary of the irregular wire layout region is spread among all irregular spacings S6B1-S6B6 in the irregular wire layout region of FIG. 5B, whereas the extra space required to re-synchronize regular wires to the VG at the boundary of the irregular wire layout region is focused in the irregular spacing S6A1 between the two irregular wires 662 and 663 in the irregular wire layout region of FIG. 5A. It should be understood that an irregular spacing may be less than a standard spacing. For example, the irregular spacing S6B1 may be less than the standard spacing SS6 in FIG. 5B.

FIG. 5C shows an exemplary layout with irregular wires 660-661 having widths W61-W62, respectively, that are less than a standard width SS6. A sub-res wire 690 of width SRW6 is placed between irregular wires 660 and 661. A spacing S6C1 exists between facing long edges of irregular wire 660 and regular wire 620. A spacing S6C2 exists between facing long edges of irregular wire 660 and sub-res wire 690. A spacing S6C3 exists between facing long edges of sub-res wire 690 and irregular wire 661. A spacing S6C4 exists between facing long edges of irregular wire 661 and regular wire 623. Use of the sub-res wire 690 avoids having a large irregular spacing between irregular wires 660 and 661, and thereby enables reduction in spacing variation, which may be beneficial to manufacturing. Also, the width SRW6 of sub-res wire 690 is somewhat adjustable so long as the sub-res wire 690 does not resolve during a manufacturing process. Therefore, in one embodiment, the irregular spacings S6C1-S6C4 may be set equal to the regular spacing SS6, if the width SRW6 of sub-res wire 690 can be correspondingly adjusted without causing resolution of the sub-res wire 690.

A method to reduce negative electrical or manufacturing influences between layout shapes or layout regions is to interpose other layout shapes between them. These interposing layout shapes may have characteristics of regular wires, irregular wires, or sub-res wires and may provide protection between regions of irregular wires and regions of regular wires. FIG. 6 shows an exemplary layout implementing the above-mentioned method. FIG. 6 shows irregular wires 760 and 761 and regular wires 710-715, 721, 722, 724, 725, 730-725. An irregular wire layout region is defined between regular wires 722 and 724. Irregular spacings S7A1-S7A3 are utilized within the irregular wire layout region. The regular wire 722 is placed adjacent to irregular wire 760. Because the regular wire 722 may shield regular wire 721 from lithographic and/or electrical influences (such as adverse light wave interference and/or capacitive coupling) of irregular wire 760, the regular wire 722 is considered a protective shape. The long regular wire 724 is placed adjacent to irregular wire 761. Similarly, because the long regular wire 724 may shield regular wire 725 from the lithographic and/or electrical influences of irregular wire 761, the long regular wire 724 is considered a protective shape. Linear layout shapes may also by defined to perform an isolating or protecting function for other layout shapes in a direction of extent of the VG. For example, regular wires such as 712-713 may prevent unwanted lithographic or electrical interactions between layout shapes or layout regions adjacent to their left edges, i.e., to their left wire ends, and irregular wires 760 and 761, which are adjacent to the right wire ends of regular wires 712-713.

Another method to increase the effectiveness of placing a protective layout shape between layout shapes or layout regions includes ensuring that the protective layout shape is unbroken (does not have gaps) and/or that it extends beyond a boundary of a layout shape/region to be protected and in the direction parallel to VG lines. For example, in the exemplary layout of FIG. 6, the protective long regular wire 724 extends beyond the line end of irregular wire 761 by a distance of DWEXT. In this manner, undesired interactions, such as adverse lithographic and/or electrical influences, between irregular wire 761 and regular wires 715 and 725 are further reduced.

Another method to reduce negative manufacturing influences between layout shapes or layout regions is to interpose sub-res shapes between them, such that the interposing sub-res shapes act as protective shapes. FIG. 7 shows a variation of the exemplary layout of FIG. 6 in which protective sub-res shapes 790 and 791 are placed in lieu of protective regular wires 722 and 724, respectively. In the exemplary layout of FIG. 7, an irregular wire layout region is defined between regular wires 721 and 725, to include irregular wires 760-761 and sub-res shapes 790-791. Each of sub-res shapes 790 and 791 is defined to have a width of SRW. Sub-res shape 790 is separated from adjacent regular wire 721 by the standard spacing SS. Irregular wire 760 is separated from sub-res shape 790 by irregular spacing S7B1. Irregular wire 761 is separated from irregular wire 760 by irregular spacing S7B2. Sub-res shape 791 is separated from irregular wire 761 by irregular spacing S7B3. Sub-res shape 791 is also separated from regular wire 725 by standard spacing SS. Sub-res shape 790 may reduce lithographic influences between layout shapes 721 and 760. Similarly, sub-res shape 791 may reduce lithographic influences between layout shapes 725 and 761.

Another method to improve the manufacturability of a layout that includes irregular wires is to optimize end gaps associated with specific wire widths, wherein the optimized end gaps may vary in size within the layout. FIG. 8A shows an exemplary layout within which end gaps are varied to improve manufacturability. FIG. 8A shows irregular wires 860-863, surrounded by regular wires 810-815, 820, 821, 824, 825, 830, 831, 834, 835, 841-845. In the example embodiment of FIG. 8A, regular wires placed end-to-end that are not adjacent to the irregular wire layout region, such as regular wires 810 and 820, have a standard end gap LS1 between their facing line ends. Regular wires placed end-to-end with irregular wires of the irregular wire layout region, such as regular wires 812 and 813 respectively placed end-to-end with irregular wires 860 and 861, may have a non-standard end gap LS2 between their facing line ends. Similarly, regular wires 842 and 843 placed end-to-end with irregular wires 862 and 863, respectively, have a non-standard end gap LS5 between their facing line ends. Also, irregular wires placed end-to-end within the irregular wire layout region, such as irregular wires 860 and 862, may have a another non-standard end gap LS3 between their facing line ends. Also, regular wires that bound the irregular wire layout region, such as regular wires 821 and 831, may have another non-standard end gap LS4 between their facing line ends. It should be understood that non-standard end gaps, such as LS2-LS5, may be defined to provide lithographic compensation or optimization necessitated by definition and placement of irregular wires within the irregular wire layout region. More specifically, particular irregular wire dimensions (width and length) and irregular wire spacings (end gap and long edge-to-long edge) within the irregular wire layout region may steer definition of non-standard end gaps within and/or around the irregular wire layout region.

For circuits that need to be matched in terms of manufactured shape characteristics and in terms of electrical influences due to neighboring elements, such as balanced circuits, use of protective layout shapes around such circuits may be combined with use of irregular wires and/or irregular spaces within such circuits to provide the necessary matching therebetween. Layout shapes within circuits to be matched may also be arranged symmetrically in X rows and Y columns. Such a symmetric arrangement may be done for structures such as common centroid structures or other circuits that require close matching between shape dimensions such as gate length and width. Also, it should be appreciated that use of protective layout shapes within and/or around a circuit layout may serve to reduce unwanted electrical coupling effects and/or unwanted lithographic interactions between layout shapes on either side of the protective layout shapes in any given direction.

In the exemplary embodiment of FIG. 8A, irregular wires 860-863 are arranged symmetrically both vertically and horizontally, i.e., in both x- and y-directions. In one embodiment, wire placement symmetry, such as that demonstrated by irregular wires 860-863, enables matching between pairs of layout shapes. For example, the combined characteristics of irregular wires 860 and 863 are matched to the combined characteristics of irregular wires 861 and 862. In one embodiment, electrically connected circuit features, such as irregular wires 860 and 863 by way of example, are placed diagonally with respect to each other. Also, a matched pair of electrically connected circuit features, such as irregular wires 861 and 862 by way of example, are placed diagonally. Furthermore, features in the matched circuit, such as irregular wires 860-863, are placed evenly around a common point in space X, also referred to a common centroid. To this end, pairs of wires in a matched circuit that are placed end-to-end, such as irregular wires 860 and 862, and irregular wires 861 and 863, are separated by the same end gap LS3. Also, pairs of wires in a matched circuit that are placed adjacent and parallel to each other, such as irregular wires 860 and 861, and irregular wires 862 and 863, are separated by the same long edge-to-long edge spacing S8A2.

Regular wires which bound a symmetrically defined irregular wire layout region may be placed such that edges of the regular wires that face toward a given side of the irregular wire layout region are positioned at a constant distance from the outward facing edges of the layout shapes within and along the given side of the irregular wire layout region. For example, regular wires 812, 813, 824, 834, 843, 842, 831, and 821 which bound the irregular wire layout region shown in FIG. 8A, may be placed such that their edges which face toward the irregular wire layout region are a constant distance from respective facing edges of irregular wires 860-863 along a given side of the irregular wire layout region. For instance, edges of regular wires 812 and 813 which face toward the irregular wire layout region are a constant distance LS2 from respective facing edges of irregular wires 860 and 861. Edges of regular wires 824 and 834 which face toward the irregular wire layout region are a constant distance S8A3 from respective facing edges of irregular wires 861 and 863. Edges of regular wires 843 and 842 which face toward the irregular wire layout region are a constant distance LS5 from respective facing edges of irregular wires 863 and 862. Edges of regular wires 831 and 821 which face toward the irregular wire layout region are a constant distance S8A1 from respective facing edges of irregular wires 862 and 860. Additionally, further regularity may be achieved in the symmetrically defined irregular wire layout region if some of the peripheral spacings (LS2, S8A3, LS5, S8A1) are made equal, e.g., LS2=LS5 and/or S8A1=S8A3. It should be understood that the regular wires which bound an irregular wire layout region, (such as regular wires 811-814, 821, 824, 831, 834, 841-844) may be used as protective layout shapes and/or may be used to perform a circuit function.

FIG. 8B shows an exemplary layout in which long regular wires are used to bound an irregular wire layout region, thereby serving as protective layout shapes between the irregular wire layout region and a surrounding layout area. Long regular wires 811P and 814P are each placed to bound a respective side of an irregular wire layout region within which irregular wires 860-863 are symmetrically arranged in a common centroid fashion around point X. Each of the long regular wires 811P and 814P is defined to extend beyond outer edges of outermost irregular wires. For example, long regular wire 814P is defined to extend beyond an outer edge of irregular wire 863 by a distance DWEXT. The unbroken nature of the long regular wires 811P and 814P and their extension beyond the outer edges of the outermost irregular wires may provide protection against adverse manufacturing or electrical influences between irregular shapes 860-863 and regular shapes 810, 820, 830, 815, 825, 835, and 845 placed on an opposing side of long regular wires 811P and 814P. Regular wires 812, 813, 842, and 843 which are respectively placed end-to-end with irregular wires 860-863 may reduce unwanted interactions between irregular wires 860-863 and other layout shapes, such as layout shapes placed to the left of regular wires 812 and 813 or layout shapes placed to the right of regular wires 842 and 843.

Another method to reduce unwanted lithographic interactions between two layout shapes is to interpose a sub-res wire between the two layout shapes, as an alternative to the previously described method of interposing regular wires. Because the sub-res shape is not manufactured, one advantage of using a sub-res shape is that capacitive coupling between manufactured shapes that are separated by the sub-res shape is reduced. Therefore, a conductor-to-conductor separation distance associated with facing edges of two manufactured shapes is increased when a sub-res shape is used as an interposed protective layout shape, relative to when a regular wire is used as the interposed protective layout shape. FIG. 8C shows a variation of the exemplary layout of FIG. 8B, in which sub-res shapes 890 and 891 are used in lieu of long regular wires 811P and 814P, respectively. Each of sub-res shapes 890 and 891 is defined to have a width SRW, such that the sub-res shape will not resolve during manufacturing. The sub-res shape 890 reduces lithographic interaction between the irregular wires 860-863 and the regular wires 810, 820, 830 that are placed opposite the sub-res shape 890 from the irregular wire layout region. The sub-res shape 891 reduces lithographic interaction between the irregular wires 860-863 and the regular wires 815, 825, 835, 845 that are placed opposite the sub-res shape 891 from the irregular wire layout region. In the portion of the as-manufactured chip level associated with the layout of FIG. 8C, a large space SMANUF is present between the facing long edges of regular wire 820 and irregular wire 860, and between the facing long edges of regular wire 830 and irregular wire 862. It should be appreciated that the space SMANUF is larger that a long edge-to-long edge spacing S8B1 between the regular wire 811P and the irregular wires 860 and 862 in the layout of FIG. 8B. Therefore, the capacitive coupling experienced by irregular wires 860 and 862 may be reduced by the larger conductor-to-conductor spacing SMANUF, relative to the spacing S8B1.

The use of protective layout shapes may also be helpful in preventing unwanted interactions between an area of higher layout shape density and an area of lower layout shape density, as variations in layout shape density may adversely affect lithographic results. FIG. 8D shows a layout region 1199 immediately adjacent to a long edge 1114A of a linear layout shape 1114. Layout shape 1114 may protect layout shapes placed opposite the layout shape 1114 from the layout region 1199, such as layout shapes 1160-1163, from adverse lithographic effects related to layout shapes within layout region 1199. In one embodiment, layout region 1199 may have a lower layout shape density relative to the layout region defined opposite the linear layout shape 1114. For example, a long edge-to-long edge spacing S114, between linear layout shape 1114 and adjacently placed layout shape 1170 within the layout region 1199, may be significantly larger than long edge-to-long edge spacings S113 and S112 within the layout region defined opposite the linear layout shape 1114. The lithographic influence of region 1199 on wires 1161 and 1163 may be reduced by the presence of linear layout shape 1114 acting as a protective layout shape.

The use of regular wires and sub-res shapes as protective layout shapes, such as described with regard to FIGS. 8B and 8C, can be applied to protect either regular wires or irregular wires. FIG. 8E shows an exemplary layout in which regular wires 880-883 of standard width W1 are defined within a layout region R8D. Protective layout shapes 890, 891, 812, 813, 842, and 843 serve to protect regular wires 880-883 from adverse lithographic and/or electrical influence by layout shapes/regions defined outside of the layout region R8D. It should be appreciated that some or all of protective layout shapes 890, 891, 812, 813, 842, and 843 may be sub-res shapes.

Layout shapes can be arranged in a number of ways to optimize circuit balancing. FIG. 8F shows an exemplary layout that includes a symmetrical arrangement of irregular wires 860-863. Top edges of irregular wires 860 and 862 are substantially aligned with, or near to aligned with, top edges of neighboring regular wires 830 and 841, thereby resulting in a long edge-to-long edge spacing S8E1 between regular wire 810P and each of irregular wires 860 and 862 that is substantially equivalent to standard spacing SS. Bottom edges of irregular wires 861 and 863 are substantially aligned with, or near to aligned with, bottom edges of neighboring regular wires 813 and 843, thereby resulting in a long edge-to-long edge spacing S8E2 between regular wire 814P and each of irregular wires 861 and 863 that is substantially equivalent to standard spacing SS. Spacing S8E5 between facing long edges of irregular shapes such as 860 and 861 may not be equivalent to or near the standard spacing SS. Although similar to the exemplary layout of FIG. 3C, the exemplary layout of FIG. 8F includes a common centroid style irregular wire layout arrangement.

FIG. 8G shows a variation of the exemplary layout of FIG. 8F in which a layout shape 822P is inserted between symmetrically arranged irregular wires 860-863. Layout shape 822P may be a dummy shape or may be used for a circuit function. A width W3 of layout shape 822P may be regular, irregular, or small enough that the layout shape 822P is a sub-res shape. Facing long edges of irregular wire 860 and layout shape 822P are separated by spacing S8F3. Similarly, facing long edges of irregular wire 862 and layout shape 822P are separated by spacing S8F3. Facing long edges of irregular wire 861 and layout shape 822P are separated by spacing S8F4. Similarly, facing long edges of irregular wire 863 and layout shape 822P are separated by spacing S8F4. The spacings S8F3 and S8F4 may be closer to standard spacing SS than the spacing S8E5 in the layout of FIG. 8F, in which the interposing shape 822P is not present.

Although the exemplary layouts depicted in FIGS. 8A-8G include irregular wire layout regions arranged in two rows and two columns around a common center point (common centroid), it should be understood that the irregular wires in the irregular wire layout region can be arranged in essentially any manner. For example, in various embodiments, the irregular wires in the irregular wire layout region can be arranged in an array defined by a variable number of layout shape columns and a variable number of layout shape rows.

FIG. 8H shows an exemplary layout in which irregular wires 870-873 are arranged in an array defined by four layout shape columns and one layout shape row. In one embodiment, matching is required between interleaved pairs of irregular wires such that the combined characteristics of irregular wires 870 and 872 are matched to the combined characteristics of irregular wires 871 and 873. The exemplary layout of FIG. 8H also includes protective shapes defined by wires 890, 891, 812 and 842, which reduce lithographic and/or electrical interactions between irregular wires 870-873 and regular wires opposite the protective shapes from the irregular wire layout region, such as regular wires 810, 820, and 813. A respective width of each protective wire 890, 891, 812 and 842 may be regular, irregular, or small enough that the protective wire is a sub-res shape. Spacings S8H1-S8H7 that extend perpendicularly away from long edges of irregular wires may not be equal to standard spacing SS.

Another method to reduce spacing variation is to modify one or more irregular wire widths such that long edge-to-long edge spacing after placement is satisfactory. This method may be used in conjunction with other methods and embodiments shown herein. One embodiment of this method is shown in FIG. 9A, in which an irregular wire 960 is placed in an area including regular wires 910-913, 920, and 923. A width W960 of irregular wire 960 is set such that spacing variations associated with the irregular wire 960 is acceptable, wherein these spacing variations are defined as the differences between standard spacing SS and each of spacings S9A1 and S9A2. In one embodiment, these spacing variations are eliminated by setting the width W960 and the placement of irregular wire 960, such that S9A1=S9A2=SS.

Another embodiment is shown in FIG. 9B, where two irregular wires 961 and 962 having widths W961 and W962, respectively, are successively placed between regular wires 920 and 924. Long edge-to-long edge spacings associated with irregular shapes 961 and 962 are shown as S9B1, S9B2, and S9B3. In one embodiment, irregular wire widths W961 and W962 are set such that spacing variations associated with irregular wires 961 and 962 are reduced to an acceptable value, wherein these spacing variations are defined as SV9B1=|S9B1−SS|, SV9B2=|S9B2−SS|, and SV9B3=|S9B3−SS|. In one embodiment, each of spacing variations SV9B1, SV9B2, and SV9B3 can be eliminated if W961, W962 and the placement of irregular wires 961 and 962 are defined such that S9B1=S9B2=S9B3=SS.

Another embodiment is shown in FIG. 9C, where irregular shapes 971, 972, and 990 having widths W971, W972, and W990, respectively, are placed between regular wires 920 and 924. Long edge-to-long edge spacings associated with irregular wires 971, 990, and 972 are shown as S9C1, S9C2, S9C3, and S9C4. Width W990 can be set to a value less than standard width W1 to compensate for widths W971 and W972 that are greater than standard width W1, so as to set each of spacings S9C1, S9C2, S9C3, and S9C4 sufficiently similar to standard spacing SS. In one embodiment, the width W990 may be small enough to make wire 990 a sub-res shape. In one embodiment, all spacing variation can be eliminated if W971, W972, W990, and the placement of shapes 971, 972, and 990 are such that S9C1=S9C2=S9C3=S9C4=SS.

In the methods and exemplary layouts previously described, irregular wires and sub-res shapes may or may not be centered on a VG line, on which regular wires are centered. Another method for formation and placement of irregular wires includes placement of irregular wires such that centerlines of the irregular wires are coincident with VG lines to a maximum extent possible, while minimizing an impact of non-standard width wires on overall layout pattern regularity.

FIG. 10A shows an exemplary layout in which an irregular wire 1030 is placed such that its centerline is coincident with a VG line 102. Irregular wire 1030 is placed within an irregular wire region bounded by regular wires 1010-1014, 1020, and 1024. VG lines 101 and 103 are unpopulated within the irregular wire layout region. With each layout shape centered on VG line and with no long edge-to-long edge spacings less than standard spacing SS, placement of irregular wire 1030 on VG line 102 results in long edge-to-long edge spacings of S10A1 and S10A2. In this embodiment, spacing variation (SV10A=|S10A1−SS|) may be significant.

FIG. 10B shows a variation of the exemplary layout of FIG. 10A in which irregular wire 1030 is moved up to VG line 101, and regular wire 1024 is moved up to VG line 102. This results in non-standard spacings S10B1 and S10B2, which are less than standard spacing SS. Spacing variation may be less in a layout that does not skip VG lines to accommodate irregular wire placement, as compared to a layout that does skip VG lines to accommodate irregular wire placement, such as shown in FIG. 10A. However, where an irregular wire width is wider than the standard width of regular wires, placement of the irregular wire may result in irregular spacing that is too small to pass manufacturing design rule checks.

FIG. 10C shows a variation of the exemplary layout of FIG. 10A in which layout shapes 1060 and 1061 are inserted in long edge spaces S10A1 and 510A2 on each side of irregular wire 1030. Insertion of layout shapes 1060 and 1061 creates long edge-to-long edge spacings S10C1-S10C4, which may be closer to standard spacing SS than long edge spaces S10A1 and S10A2. In one embodiment, layout shapes 1060 and 1061 may be sub-res shapes.

It should be understood that the methods for defining an irregular wire layout region within the dynamic array architecture as disclosed herein can be implemented in a layout that is stored in a tangible form, such as in a digital format on a computer readable medium. For example, the layout defined in accordance with the methods disclosed herein can be stored in a layout data file of one or more cells, selectable from one or more libraries of cells. The layout data file can be formatted as a GDS II (Graphic Data System) database file, an OASIS (Open Artwork System Interchange Standard) database file, or any other type of data file format suitable for storing and communicating semiconductor device layouts. Also, multi-level layouts defined in accordance with the methods disclosed herein can be included within a multi-level layout of a larger semiconductor device. The multi-level layout of the larger semiconductor device can also be stored in the form of a layout data file, such as those identified above.

Also, the invention described herein can be embodied as computer readable code on a computer readable medium. For example, the computer readable code can include the layout data file within which one or more layouts defined in accordance with the methods disclosed herein are stored. The computer readable code can also include program instructions for selecting one or more layout libraries and/or cells that include a layout defined in accordance with the methods disclosed herein. The layout libraries and/or cells can also be stored in a digital format on a computer readable medium.

The computer readable medium mentioned herein is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include hard drives, network attached storage (NAS), read-only memory, random-access memory, CD-ROMs, CD-Rs, CD-RWs, magnetic tapes, and other optical and non-optical data storage devices. The computer readable medium can also be distributed over a network of coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

Any of the operations described herein that form part of the invention are useful machine operations. The invention also relates to a device or an apparatus for performing these operations. The apparatus may be specially constructed for the required purpose, such as a special purpose computer. When defined as a special purpose computer, the computer can also perform other processing, program execution or routines that are not part of the special purpose, while still being capable of operating for the special purpose. Alternatively, the operations may be processed by a general purpose computer selectively activated or configured by one or more computer programs stored in the computer memory, cache, or obtained over a network. When data is obtained over a network the data maybe processed by other computers on the network, e.g., a cloud of computing resources.

The embodiments of the present invention can also be defined as a machine that transforms data from one state to another state. The data may represent an article, that can be represented as an electronic signal and electronically manipulate data. The transformed data can, in some cases, be visually depicted on a display, representing the physical object that results from the transformation of data. The transformed data can be saved to storage generally, or in particular formats that enable the construction or depiction of a physical and tangible object. In some embodiments, the manipulation can be performed by a processor. In such an example, the processor thus transforms the data from one thing to another. Still further, the methods can be processed by one or more machines or processors that can be connected over a network. Each machine can transform data from one state or thing to another, and can also process data, save data to storage, transmit data over a network, display the result, or communicate the result to another machine.

It should be further understood that the layouts defined in accordance with the methods disclosed herein can be manufactured as part of a semiconductor device or chip. In the fabrication of semiconductor devices such as integrated circuits, memory cells, and the like, a series of manufacturing operations are performed to define features on a semiconductor wafer. The wafer includes integrated circuit devices in the form of multi-level structures defined on a silicon substrate. At a substrate level, transistor devices with diffusion regions are formed. In subsequent levels, interconnect metallization lines are patterned and electrically connected to the transistor devices to define a desired integrated circuit device. Also, patterned conductive layers are insulated from other conductive layers by dielectric materials.

While this invention has been described in terms of several embodiments, it will be appreciated that those skilled in the art upon reading the preceding specifications and studying the drawings will realize various alterations, additions, permutations and equivalents thereof. Therefore, it is intended that the present invention includes all such alterations, additions, permutations, and equivalents as fall within the true spirit and scope of the invention. 

What is claimed is:
 1. An integrated circuit, comprising: a first conductive structure having a first length as measured in a first direction and a first width as measured in a second direction perpendicular to the first direction, the first conductive structure having a lengthwise centerline positioned on a first virtual line of a virtual grate, the virtual grate including a plurality of lines spaced at a uniform pitch; a second conductive structure having a second length as measured in the first direction and a second width as measured in the second direction, the second width substantially equal to the first width, the second conductive structure having a lengthwise centerline positioned on a second virtual line of the virtual grate, the virtual grate including at least two virtual lines interposed between the first virtual line and the second virtual line; a third conductive structure having a third length as measured in the first direction and a third width as measured in the second direction, the third width less than the second width, the third conductive structure positioned beside the second conductive structure and between the first conductive structure and the second conductive structure, the third conductive structure separated from the second conductive structure by a first spacing as measured in the second direction; and a fourth conductive structure having a fourth length as measured in the first direction and a fourth width as measured in the second direction, the fourth width substantially equal to the third width, the fourth conductive structure positioned beside the first conductive structure and between the first conductive structure and the second conductive structure, the fourth conductive structure separated from the first conductive structure by the first spacing as measured in the second direction.
 2. The integrated circuit as recited in claim 1, wherein a lengthwise centerline of the third conductive structure is not positioned on a virtual line of the virtual grate.
 3. The integrated circuit as recited in claim 3, wherein a lengthwise centerline of the fourth conductive structure is not positioned on a virtual line of the virtual grate.
 4. The integrated circuit as recited in claim 1, wherein the first length is substantially equal to the second length.
 5. The integrated circuit as recited in claim 4, wherein the third length is substantially equal to the fourth length.
 6. The integrated circuit as recited in claim 1, wherein the third length is substantially equal to the fourth length.
 7. The integrated circuit as recited in claim 1, wherein the first width is at least two times the third width.
 8. The integrated circuit as recited in claim 1, wherein the first conductive structure has a first end and a second end, wherein the second conductive structure has a first end and a second end, and wherein the first end of the first conductive structure and the first end of the second conductive structure are substantially aligned to a same location in the first direction.
 9. The integrated circuit as recited in claim 8, wherein the third conductive structure has a first end and a second end, wherein the fourth conductive structure has a first end and a second end, and wherein the first end of the third conductive structure and the first end of the fourth conductive structure are substantially aligned to a same location in the first direction.
 10. The integrated circuit as recited in claim 1, wherein the third conductive structure has a first end and a second end, wherein the fourth conductive structure has a first end and a second end, and wherein the first end of the third conductive structure and the first end of the fourth conductive structure are substantially aligned to a same location in the first direction.
 11. The integrated circuit as recited in claim 1, further comprising: a fifth conductive structure having a fifth length as measured in the first direction and a fifth width as measured in the second direction, the fifth width substantially equal to the third width, the fifth conductive structure positioned between the third conductive structure and the fourth conductive structure.
 12. The integrated circuit as recited in claim 11, wherein the fifth conductive structure is separated from the third conductive structure by the first spacing as measured in the second direction.
 13. The integrated circuit as recited in claim 11, wherein the fifth conductive structure is separated from the fourth conductive structure by the first spacing as measured in the second direction.
 14. The integrated circuit as recited in claim 11, further comprising: a sixth conductive structure having a sixth length as measured in the first direction and a sixth width as measured in the second direction, the sixth width substantially equal to the third width, the sixth conductive structure positioned between the third conductive structure and the fourth conductive structure.
 15. The integrated circuit as recited in claim 14, wherein the fifth conductive structure is separated from the third conductive structure by the first spacing as measured in the second direction, and wherein the sixth conductive structure is separated from the fourth conductive structure by the first spacing as measured in the second direction.
 16. The integrated circuit as recited in claim 15, wherein the first conductive structure has a first end and a second end, wherein the second conductive structure has a first end and a second end, and wherein the first end of the first conductive structure and the first end of the second conductive structure are substantially aligned to a same location in the first direction.
 17. The integrated circuit as recited in claim 16, wherein the third conductive structure has a first end and a second end, wherein the fourth conductive structure has a first end and a second end, and wherein the first end of the third conductive structure and the first end of the fourth conductive structure are substantially aligned to a same location in the first direction.
 18. The integrated circuit as recited in claim 17, wherein the fifth conductive structure has a first end and a second end, wherein the sixth conductive structure has a first end and a second end, and wherein the first end of the fifth conductive structure and the first end of the sixth conductive structure are substantially aligned to a same location in the first direction.
 19. The integrated circuit as recited in claim 15, further comprising: a seventh conductive structure having a seventh length as measured in the first direction and a seventh width as measured in the second direction, the seventh width substantially equal to the third width, the seventh conductive structure positioned between the fifth conductive structure and the sixth conductive structure.
 20. The integrated circuit as recited in claim 19, wherein the seventh conductive structure is separated from the fifth conductive structure by the first spacing as measured in the second direction, or the seventh conductive structure is separated from the sixth conductive structure by the first spacing as measured in the second direction.
 21. A method for manufacturing an integrated circuit, comprising: forming a first conductive structure having a first length as measured in a first direction and a first width as measured in a second direction perpendicular to the first direction, the first conductive structure having a lengthwise centerline positioned on a first virtual line of a virtual grate, the virtual grate including a plurality of lines spaced at a uniform pitch; forming a second conductive structure having a second length as measured in the first direction and a second width as measured in the second direction, the second width substantially equal to the first width, the second conductive structure having a lengthwise centerline positioned on a second virtual line of the virtual grate, the virtual grate including at least two virtual lines interposed between the first virtual line and the second virtual line; forming a third conductive structure having a third length as measured in the first direction and a third width as measured in the second direction, the third width less than the second width, the third conductive structure positioned beside the second conductive structure and between the first conductive structure and the second conductive structure, the third conductive structure separated from the second conductive structure by a first spacing as measured in the second direction; and forming a fourth conductive structure having a fourth length as measured in the first direction and a fourth width as measured in the second direction, the fourth width substantially equal to the third width, the fourth conductive structure positioned beside the first conductive structure and between the first conductive structure and the second conductive structure, the fourth conductive structure separated from the first conductive structure by the first spacing as measured in the second direction. 